Dentrifice composition

ABSTRACT

A non-aqueous dentifrice composition suitable as a vehicle for materials that are incompatible (i.e. have a limited solubility or react) with an aqueous enviroment. Accordingly, the present invention provides a non-aqueous dentifrice composition comprising a carboxyvinyl polymer, a humectant, a polyethylene glycol and a dentally acceptable abrasive.

This application is a 371 of PCT/EP95/02826 Jul. 18, 1995.

The present invention relates to a dentifrice composition, in particularto a non-aqueous (anhydrous) dentifrice composition. Such non-aqueouscompositions may then suitably contain other materials which areunstable and incompatible with an aqueous environment.

There are many materials which have limited solubility in or even reactwith the aqueous systems of typical dentifrice formulations. One way ofovercoming this problem during formulation is to encapsulate these watersensitive materials to prevent them from interacting with the aqueouscomponent(s) present in the dentifrice formulation. Althoughencapsulation is a well known and used technique that can be usefullyemployed in the formulation of dentifrice compositions, it does notcompletely solve the problem as the encapsulated material frequentlycontacts water in the remainder of the product due to diffusion or`capsule fracture`.

Other methods of improving the stability of these materials have beensuggested and these include the use of anhydrous compositions.

U.S. Pat. No. 4,988,500 (Hunter et al) which has been assigned to TheProcter & Gamble Company discloses and claims an anhydrous oralcomposition comprising a carboxyvinyl polymer, a neutralising agent, aperoxide or perborate compound and an anhydrous humectant. It is howevernecessary to neutralise the carboxyvinyl polymer in order to obtaindentifrice compositions that provide acceptable viscositycharacteristics.

U.S. Pat. No. 4,647,451 (Piechota) which has been assigned toColgate-Palmolive Company describes an anhydrous dentifrice containing apolysaccharide gum and a glycerine humectant. Polyethylene glycol isoptionally added as a dispersion agent.

It has now been discovered that the problems associated with formulatingand administering a dentifrice with ingredients that are incompatiblewith the aqueous phase may be solved by the use of an improvednon-aqueous formulation that is as acceptable as conventional dentifriceformulations.

Accordingly, the present invention provides a non-aqueous dentifricecomposition comprising a carboxyvinyl polymer, a humectant, apolyethylene glycol and a dentally acceptable abrasive.

The carboxyvinyl polymer is used in the acid form, and does notnecessarily require any form of neutralising.

Carboxyvinyl polymers will thicken humectant materials and also providethe necessary rheology in order to suspend any required abrasivematerial.

The term `rheology` as used herein is intended to reflect the flowcharacteristics of the formulation.

Suitable carboxyvinyl polymers for use in dentifrices of the inventionare copolymers of acrylic acid cross-linked with polyallylsucrose, forexample Carbopol 974 and 934 or cross-linked with divinyl glycol, forexample Noveon AA-1. Carbopol polymers are manufactured by B.F. GoodrichCompany. Carbopol 974 is preferred.

The carboxyvinyl polymer may be present in the range of from 0.1 to 7.5%w/w, preferably from 0.3 to 1.0%, more preferably about 0.35% by weightof the dentifrice.

Suitable humectants for use in the present invention include glycerine,sorbitol and propylene glycol or mixtures thereof. It is well known thatcommercially available glycerine may contain between 0.5-2.0% by weightof water which is in association with the glycerine. Typically thisamount is between 0.5-1.0% by weight. This small amount of water ifbound to the glycerine and is therefore not available to the otheringredients. The skilled person would still consider a compositioncontaining glycerine as being non-aqueous. The humectants should in anycase be as anhydrous as possible and preferably used in solid form.

Glycerine is the preferred humectant.

As the humectant is used to make the formulations up to 100%, thehumectant may be present in the range of from 20 to 90% by weight of thedentifrice. Preferably the humectant is present from 35 to 75%, morepreferably from 45 to 70% by weight of the dentifrice.

The polyethylene glycol is selected so that it will reduce anystickiness from the formulation and give a smooth textured product.Suitably, the polyethylene glycol will be selected from PEG 300 and PEG400. PEG 400 is preferred.

Advantageously, the polyethylene glycol is present in the range of from0.1 to 40%, preferably 15 to 20% by weight of the dentifrice.

It is perhaps more suitable to refer to the ratio of carboxyvinylpolymer to polyethylene glycol that is required in order to produce aproduct that is smooth and does not show any signs of stickiness.

Advantageously the ratio of carboxyvinyl polymer to polyethylene glycolis in the range of 1:15 to 1:20, preferably 1:17.5.

Suitable abrasives for use in the present invention include, forexample, silica, zinc orthophosphate, sodium bicarbonate (baking soda),plastic particles, alumina, hydrated alumina, calcium carbonate andcalcium pyrophosphate or mixtures thereof.

The silica abrasive may be a natural amorphous silica, for instancediatomaceous earth; or a synthetic amorphous silica such as aprecipitated silica, for instance `Tixosil 53B`, manufactured by RhonePoulenc, or a silica gel, such as a silica xerogel; or mixtures thereof.

Generally, an amount of abrasive suitable for use in the dentifricecomposition of the present invention will be empirically determined toprovide an acceptable level of cleaning and polishing, in accordancewith the techniques well known in the art. Suitably, the abrasive willbe present in from about 5 to about 60%, preferably from about 5 toabout 30%, by weight of the dentifrice.

Advantageously a thickening agent is present in the formulation to givethe product a rheology closer to that of a conventional dentifrice.Suitably the thickening agent is a thickening silica, for instance`Sident 22S`, which is manufactured by Degussa Ltd.

The thickening silica will be in the range of from 0.01 to 10%,preferably 5.0 to 7.0% by weight of the dentifrice.

Surfactant materials are usually added to dentifrice products to providecleaning and/or foaming properties. Any conventional surfactant used indentifrice formulations may be used in the present invention, providedthat it can be added as a solid powder, that is not in an aqueoussolution.

Suitable surfactants include anionic, cationic, nonionic and amphotericsurfactants.

Suitable nonionic surfactants include, for example polyethoxylatedsorbitol esters, in particular polyethoxylated sorbitol monoesters, forinstance, PEG(40) sorbitan diisostearate, and the products marketedunder the trade name `Tween` by ICI; polycondensates of ethylene oxideand propylene oxide (poloxamers), for instance the products marketedunder the trade name `Pluronic` by BASF-Wyandotte; condensates ofpropylene glycol; polyethoxylated hydrogenated castor oil, for instance,cremophors; and sorbitan fatty esters.

Suitable anionic surfactants include, for example sodium laurylsulphate, marketed by Albright and Wilson and known as `SLS`. This maybe obtained and is used in a powder form in the present invention.

A particularly preferred anionic surfactant is sodium methyl cocyltaurate, marketed under the trade name `Adinol CT 95` manufactured byCroda chemicals.

Advantageously, the surfactant is present in the range 0.005 to 20%,preferably 0.1 to 10%, more preferably 0.1 to 5% by weight of thedentifrice.

Advantageously a dentifrice according to the invention may furthercomprise an ionic fluorine-containing compound, which may include ionicfluorides, such as alkali metal fluorides, amine fluorides and ionicmonofluorophosphates, such as alkali metal monofluorophosphates, andwhich may be incorporated into the formulation, to provide between 100and 3000 ppm, preferably 500 to 2000 ppm of fluoride. Preferably theionic fluoride or monofluorophosphate is an alkali metal fluoride ormonofluorophosphate, for instance sodium fluoride or sodiummonofluorophosphate, respectively. Stannous fluoride which is not usedin conventional dentifrice formulations owing to its instability in anaqueous environment, may also be used at the above levels.

Calcium glycerophosphate which has been shown to enhance the activity ofionic monofluorophosphates, may be optionally added when the fluoridesource is an ionic monofluorophosphate.

It will further be appreciated that if an ionic fluorine-containingcompound is incorporated in a dentifrice of the invention, the abrasiveshould be chosen so that it is compatible with the ionicfluorine-containing compound. Thus, for instance, sodium fluoride iswell known in the art to be incompatible with abrasives with compriseexcess calcium ions as these cause loss of fluoride as insoluble calciumfluoride. Accordingly an abrasive which is insoluble, for instance, asilica, alumina, zinc orthophosphate or plastic particles, is preferred.Alternatively, a calcium abrasive, for instance calcium carbonate, maybe used with an alkali metal monofluorophosphate, sodiummonofluorophosphate.

Dentifrices according to the invention may also contain other agentsconventionally used in dentifrice formulations, for example colouringagents, whitening agents, for example titanium dioxide; preservativesand sweetening agents. Anti-plaque agents, for example triclosan,chlorhexidine, cetyl pyridinium chloride and nicin (preferably in apurified form, and available as Ambicin N), anti-calculus agents, forexample pyrophosphate salts, anti-sensitivity agents, for examplestrontium or potassium salts, polymer enhancing agents, for exampleGantrez may also be present if required. Breath freshening agents, forexample, sodium bicarbonate and tooth whitening agents, for examplehydrogen peroxide and sodium tripolyphosphate may also be included atappropriate levels.

In general, such agents will be in a minor amount or proportion of theformulation, usually present in from 0.001 to 5% by weight of thecomposition. Any active ingredient or combination of actives that areunstable or incompatible in any way with aqueous environments may alsobe added to the formulation of the present invention. Flavouring agentsmay also be added to the formulations, usually at a typical level of1.0% by weight of the composition.

Suitable sweetening agents include saccharin, cyclamate and acesulfameK, and may be present in from 0.01 to 0.5%, preferably 0.05 to 0.5% byweight of the dentifrice. An auxiliary sweetener such as a thaumatin mayalso be included, at a level of from 0.001 to 0.1, preferably 0.005 to0.05% by weight of the dentifrice. A suitable blend of thaumatins ismarketed under the trade name `TALIN` by Tate and Lyle plc.

Dentifrices according to the invention may also contain an antistainagent. Suitable antistain agents include, for example, carboxylic acidssuch as those disclosed in U.S. Pat. No. 4,256,731, amino carboxylatecompounds such as those disclosed in U.S. Pat. No. 4,080,441 andphosphonoacetic acid, as disclosed in U.S. Pat. No. 4,118,474. Theantistain agent may be incorporated into the dentifrice formulation ormay be provided as a separate composition, for use after the dentifrice.

The dentifrices according to the invention may have an initial viscosityof 25,000 to 100,000 centipoise which is essential for producing aproduct that is comparable to conventionl dentifrices that have consumeracceptability. The pH of the formulation when diluted in the ratio of3:1 with water should be less than 8.0.

The viscosity of the dentifrice is measured using a TF 20 spindleBrookfield Viscometer.

The dentifrices according to the invention may be prepared in aconventional manner by mixing the ingredients thereof in the requiredproportions and in any order which is convenient and, thereafter and ifnecessary, adjusting the pH. In a particularly preferred process thepolyvinyl polymer and the humectant are vigourously agitated together,with heat, for example to a temperature of for example 50°-70° C., ifneccessary, in order to give a satisfactory viscosity. Polyethyleneglycol and a thickening silica are then added to the mixture andabrasive is then dispersed in it, using a heavy-duty mixing machine.Active agents, such as a fluoride salt (if present) are then added,followed by surfactant and flavouring agents in the final stage; withfinal mixing carried out under vacuum.

The following examples illustrate the invention.

EXAMPLE 1

    ______________________________________    INGREDIENT        % w/w    ______________________________________    CARBOPOL 974P     1.00    THICKENING SILICA 4.00    ABRASIVE SILICA   14.00    SODIUM FLUORIDE   0.23    TITANIUM DIOXIDE  1.00    ADINOL CT 95      2.00    SACCHARIN         0.33    POLYETHYLENE      17.50    GLYCOL(400)    FLAVOUR           1.00    GLYCERIN          qs    ______________________________________

EXAMPLE 2

    ______________________________________    INGREDIENT        % w/w    ______________________________________    CARBOPOL 974P     1.00    THICKENING SILICA 6.50    ABRASIVE SILICA   14.00    SODIUM FLUORIDE   0.23    TITANIUM DIOXIDE  1.00    ADINOL CT 95      2.00    SACCHARIN         0.33    POLYETHYLENE      17.50    GLYCOL(400)    GLYCERIN          qs    ______________________________________

EXAMPLE 3

    ______________________________________    INGREDIENT        % w/w    ______________________________________    CARBOPOL 974P     0.50    THICKENING SILICA 6.50    ABRASIVE SILICA   14.00    SODIUM FLUORIDE   0.23    TITANIUM DIOXIDE  1.00    ADINOL CT 95      2.00    SACCHARIN         0.33    POLYETHYLENE      17.50    GLYCOL(400)    GLYCERIN          qs    ______________________________________

EXAMPLE 4

    ______________________________________    INGREDIENT        % w/w    ______________________________________    CARBOPOL 974P     0.35    THICKENING SILICA 6.50    ABRASIVE SILICA   14.00    SODIUM FLUORIDE   0.23    TITANIUM DIOXIDE  1.00    ADINOL CT 95      2.00    SACCHARIN         0.33    POLYETHYLENE      17.50    GLYCOL(400)    GLYCERIN          qs    ______________________________________

EXAMPLE 5

    ______________________________________    INGREDIENT        % w/w    ______________________________________    CARBOPOL 974P     0.35    THICKENING SILICA 6.50    ABRASIVE SILICA   14.00    SODIUM FLUORIDE   0.23    TITANIUM DIOXIDE  1.00    ADINOL CT 95      2.00    SACCHARIN         0.33    POLYETHYLENE      6.20    GLYCOL(400)    GLYCERIN          qs    ______________________________________

Carbopol 974 P is a Tradename of Goodrich plc.

Adinol CT 95 is a Tradename of Croda Chemicals.

We claim:
 1. A non-aqueous, non-stringy, smooth textured, non-stickypaste dentifrice composition comprising 0.1% to 7.5% by weight of anunneutralized carboxyvinyl polymer in the acid form, an anhydroushumectant, 0.1 to 40% by weight of a polyethylenc glycol solvent forsaid unneutralized carboxyvinyl polymer imparting smooth texture andreduced stickiness and a dentally acceptable abrasive and thickeningsilica wherein the ratio of carboxyvinyl polymer to polyethylene glycolis 1:15 to 1:2, and wherein the initial viscosity of the dentifriceranges between 25,000 and 100,000 centipoise.
 2. A composition accordingto claim 1, wherein the carboxyvinyl polymer is a copolymer of anacrylic acid crosslinked with polyallylsucrose or divinylglycol.
 3. Acomposition according to claim 1, wherein the carboxyvinyl polymer ispresent in an amount of from 0.1 to 7.5% by weight of the dentifrice. 4.A composition according to claim 1, wherein the anhydrous humectant isglycerine, sorbitol or propylene glycol or mixture-thereof.
 5. Acomposition according to claim 4, wherein the anhydrous humectant ispresent in a range of from 20 to 90% by weight of the dentifrice.
 6. Acomposition according to claim 1 wherein the abrasive is selected fromsilica, zinc orthophosphate, sodium bicarbonate, plastic particles,alumina, hydrated alumina, calcium carbonate or calcium pyrophosphate ormixtures thereof.
 7. A composition according to claim 1 additionallycomprising from 0.01-10% by weight of a thickening silica.
 8. A processfor the preparation of a composition according to claim 1 wherein thecarboxyvinyl polymer and the anhydrous humectant are vigorously agitatedtogether, with heat to give a satisfactory viscosity, after which theremaining ingredients are mixed in the required proportions.